Bayer HealthCare announced the results from a pivotal Phase 3 study for Stivarga (regorafenib); the GRID (GIST – Regorafenib In Progressive Disease) trial provides evidence for the efficacy of regorafenib in patients with gastrointestinal stromal tumor (GIST). Regorafenib is an oral multi-kinase inhibitor that inhibits various kinases that are involved in mechanisms associated with oncogenesis, angiogenesis, and the tumor microenvironment.
GRID was a randomized, double-blind, placebo-controlled, multi-center, cross-over study. It randomized 199 patients whose disease had progressed despite prior treatment with imatinib (Gleevec; Novartis) and sunitinib (Sutent; Pfizer). Patients were randomized in a 2:1 ratio to receive either regorafenib (160mg once daily, 3 weeks on/1 week off) plus best supportive care (BSC) or placebo plus BSC. Patients initially randomized to placebo were allowed to cross over to open-label regorafenib once the disease progressed, of which 85% of the patients from the placebo arm did cross over.
The trial showed that regorafenib plus BSC significantly improved progression-free survival (PFS) vs. placebo plus BSC (HR=0.27, P<0.000001). The median PFS was 4.8 months in the regorafenib arm vs. 0.9 months in the placebo arm. In addition, there was a positive trend in the regorafenib group in improving overall survival (OS) (HR=0.772, P=0.199); however, the OS did not reach statistical significance.
Furthermore, a significantly greater disease control rate (DCR) was observed with regorafenib plus BSC compared to placebo plus BSC (52.6% vs. 9.1%; P<0.000001), DCR was defined as rate of complete response [CR] plus partial response [PR] plus durable stable disease [SD] maintained for at least 12 weeks. In addition, regorafenib demonstrated therapeutic benefit independent of prior treatment options based on analysis in pre specified subgroups that showed regorafenib had a statistically significant PFS benefit over placebo for patients receiving regorafenib as a third- or fourth-line treatment.
Stivarga is approved for the treatment of patients with metastatic colorectal cancer who have been previously treated with fluoropyrimidine-, oxaliplatin– and irinotecan-based chemotherapy, an anti-VEGF therapy, and, if KRAS wild type, an anti-EGFR therapy.
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